1. Field of the Invention
The present invention relates to an electrical connector assembly.
2. Description of the Related Art
Japanese Patent Application Kokai Number 2001-143786 (FIG. 1) discloses an electrical connector assembly for connecting a plurality of circuit boards, in which an intermediate board is used.
An electrical connector assembly disclosed in the above Patent Document comprises, as shown in FIG. 6, a connector 50, which is fixed, and a mating connector 70, which is plugged into and removed from the connector 50 for electrical connection and disconnection.
(The connector 50)
The connector 50 is an intermediate connector which is made substantially symmetric vertically so that the mating connector 70 and another connector 80 having the similar structure as the mating connector 70 are connected to the connector 50 in opposite directions. The connectors 70 and 80 are usually connected to corresponding circuit boards extending in a plane perpendicular to the sheet of the drawing and the connector 50 is used for connecting these circuit boards. Since the connector 80 is fixed to an apparatus, when the connector 80 is plugged into the connector 50, the connector 80 is locked. Accordingly, for disconnection between both the circuit boards, the connector 70 is usually unplugged from the connector 50.
The connector 50 comprises an intermediate board 51 and a guide frame 52 for supporting the intermediate board 51. As shown in FIG. 6, a plurality of connection portions 53 (connection pads) are arranged laterally along upper and lower edges of the intermediate board 51. Circuit traces (not shown) are provided in the inner layer of the intermediate board 51 and connected to the connection portions 53. A thin-plate-like shield 54 is provided on substantially whole area between the upper and lower contact portions 53 to shield the circuit traces in the inner layer of the intermediate board 51. The shield 54 is connected to some of the contact portions 53. An engagement hole 55 is provided in the center of the intermediate board 51 to engage a projection 60 (described below) provided in the guide frame 52.
The guide frame 52 comprises a substantially plate-like support portion 56 for supporting the intermediate board 51 and a pair of columns which are integrally provided with the support portion 56 at ends in the lateral direction of the support portion 56.
The support portion 56 has a supporting surface for coming in contact with and supporting a substantially whole area of one face (back face in FIG. 6) of the intermediate board 51, and the projection 60 for engaging the engagement hole 55 and positioning the intermediate board 51. Each of columns has a holding portion 57 for supporting ends of the intermediate board 51 in the lateral direction and a pole-like guide portion 58 extending in the plugging direction and guiding the mating connector 70 in the plugging direction.
The guide portion 58 has a guide surface 59, a flat surface extending in the plugging direction of the mating connector 70 outside the area in which the contact portions of the intermediate board 51 are arranged. The flat surface of the guide surface 59 extends in substantially whole range of the area projecting from the edge of the intermediate board 51 in the plugging direction. The guide portion 58 guides the mating connector 70 with the guide surface 59 guiding a guided surface 74 (described below) of the mating connector 70.
(The Mating Connector 70)
The mating connector 70 comprises a housing 71, an accommodation cavity 72 provided in the housing 71 for receiving the upper edge of the intermediate board 51 in which the contact portions 53 are arranged, and a pair of hole-like guided portions 73 which are provided in the housing 71 and guided by the guide portions 58 of the guide frame 52 when the connector 70 is connected to the connector 50. A plurality of resilient contact portions of terminals (not shown) are provided in the accommodation cavity 72 at positions corresponding to those of the contact portions 53 of the intermediate board 51 so that resilient contact portions are brought into resilient contact with the contact portions 53 when the connector 70 is connected to the connector 50. The terminals extend outwardly from the opposite side of an opening of the accommodating cavity 72. The terminals have a plurality of contact portions on the opposite side which are connected by soldering to corresponding circuit traces of a circuit board (not shown) provided in a direction perpendicular the intermediate board 51.
Each of the guided portions 73 has the guided surface 74 which faces to the guide surface 59 closely when the connector 70 is connected to the connector 50 (FIGS. 6 and 7).
(Connection between both the Connectors)
As described above, the resilient contact portions of the terminals of the connector 70 are connected to the contact portions 53 provided in the upper edge of the connector 50 when the connector 70 is guided in the plugging direction. The connector 80 is also connected to the lower edge of the connector 50 in the similar way. That is, any of the connectors 70 and 80 can be a mating connector of the connector 50. Accordingly, the connectors 70 and 80 are electrically connected to each other through the connector 50. Consequently, the two circuit boards attached to the connectors 70 and 80 are electrically connected to each other under the condition that they are perpendicular to the intermediate board 51.
When disconnecting the connector 70 from the connector 50, the connector 70 is pulled out from the connector 50.
When removing the connector 70 from the connector 50, the connector 70 should not be pulled by force because the guide surface 59 and the guided surface 74 face to each other closely.
Actually, however, the connector 70 is frequently pulled by force. Especially, when the circuit board is attached to the connector 70, since the connector 70 is hidden behind the circuit board, the condition of the connector 70 is not visible accurately. Accordingly, when the connector 70 is attempted to be pulled out from the connector 50, an edge of the circuit board is grasped and the connector 70 is gouged. Under the condition, since the distance between the edge of the circuit board and the connector 70 is relatively large, the gouging force is large. The connector 70 is gouged repeatedly, being tilted in the right and left direction alternately.
When the connector 70 is gouged, as shown in FIG. 7 showing the left-hand guide portion 58, the guided surface 74 of the guided portion 73 of the connector 70 is tilted with respect to the guide surface 59 of the guide portion 58 of connector 50. Since the guide surface 59 is in close to the guided surface 74, the gap between them is small. Accordingly, if the connector 70 is gouged over the gap, the lower edge of the guided surface 74 is strongly pressed to the guide surface 59. As the result, a large force is applied to the guided and guide portions 73 and 58 and the lower edge of the guided surface 74 may bite the guide surface 59.
When the above-described large force is applied, the guide portion 58 or the guided portion 73 may be damaged, or the soldering portions between the connector 70 and the circuit board are damaged resulting in connection defective. Also, when the lower edge of the guided surface 74 bites the guide surface 59, it may be difficult to pull out the connector 70 from the connector 50.
In addition, if the removal operation of the connector 70 is finished under the condition that, for example, only the right-hand guided portion 73 in FIG. 6 is removed from the guide portion 58 and the left-hand guided portion 73 still stands in the other guide portion 58 shallowly, the connector 70 is inclined largely. In this case, since the right-hand guide portion 73 is already removed from the guide portion 58, the connector 70 rotates largely by the weight of the circuit board, which produces a force much larger than the gouging force. Accordingly, the guide portion 58 and so forth is readily damaged. Even if it does not cause the damage, the lower edge of the guided surface 74 may bite the guide surface 59, which makes it difficult for the connector 70 to be removed from the connector 50.